Fix: prompt markdownlint md040 fix for new prompts. (#10199)

* Add ESP32 Power Management lessons learned document

Documents our experimentation with ESP-IDF DFS and why it doesn't
work well for Meshtastic (RTOS locks, BLE locks, USB issues).

Proposes simpler alternative: manual setCpuFrequencyMhz() control
with explicit triggers for when to go fast vs slow.

* docs(prompts): fix markdown fence language tags

* docs: remove ESP32 power management notes

.github/prompts/new-module.prompt.md

@@ -118,7 +118,7 @@ CallbackObserver<MyModule, const meshtastic::Status *> statusObserver =
 
 Add test suite in `test/test_mymodule/`:
 
-```
+```text
 test/
 └── test_mymodule/
     └── test_main.cpp

.github/prompts/new-variant.prompt.md

@@ -6,7 +6,7 @@ Guide for adding a new Meshtastic hardware variant to the firmware.
 
 Create under `variants/<arch>/<name>/`:
 
-```
+```text
 variants/
 ├── esp32/          # ESP32
 ├── esp32s3/        # ESP32-S3